It is known that 2-methoxycarbonyl-4-chlorotrifluoromethanesulfonaniiide can be used as an active ingredient of an insecticidal/acaricidal coosition in Japanese Laid-open Patent Nos. sho-57-156407A and hei-8-319202A. However, its insecticidal/acaricidal effect may be insufficiently given when used as total release aerosol formulations or smoking formulations. Especially, the effect against Acaridae, particularly copra mite (Tyrophagus putrescentiae), that is an important object because of alergen, may be low.